Limbing boom

ABSTRACT

A limbing assembly for removing limbs from a stationary tree includes a base with a pair of parallel inner arms pivotally connected to the base. Means are provided for pivoting the inner arms relative to the base with means for maintaining the inner arms in their parallel relationship during such pivotal movement. A first arcuately-surfaced member is rigidly secured to one inner arm, a shaft is rotatably mounted in the other inner arm, and a second arcuately-surfaced member is rigidly secured to the shaft. The arcuate surfaces of the members are engaged with one another in driving relationship. An outer arm is rigidly secured at one end to the shaft. The outer arm has a length equal to the length of the other inner arm between the shaft and the base. A second shaft is rotatably mounted at the other end of the outer arm with a limbing head rigidly secured to the shaft. Means connecting the first and second shafts cause the second shaft to move through the same angle relative to the outer arm as the inner arms move relative to the base. Movement of the inner arms relative to the base causes the limbing head to travel in a straight line at a constant angular attitude relative to the base.

United States Patent (1 1 Eynon mt 3,712,350 1 .ian.23, 1973 l 54]LIMBING BOOM [76] Inventor: John E. Eynon, l03 Sunset Bay,

Port Arthur, Ontario, Canada [22] Filed: Aug. 2, 1971 [2l] Appl. No.:168,323

[51] Int. Cl. ..A0lg 23/02 [58] Field of Search ..l44/2 Z, 3 D, 34 R,309 AC [S 6] References Cited UNITED STATES PATENTS 3,554,245 1/1971Eynon ..l44/3 D Primary Examiner-Gerald A. Dost Attorney-Stevens, Davis,Miller & Mosher [57] ABSTRACT A limbing assembly for removing limbs froma stationary tree includes a base with a pair of parallel inner armspivotally connected to the base. Means are provided for pivoting theinner arms relative to the base with means for maintaining the innerarms in their parallel relationship during such pivotal movement. Afirst arcuately-surfaced member is rigidly secured to one inner arm, ashaft is rotatably mounted in the other inner arm, and a secondarcuately-surfaced member is rigidly secured to the shaft. The arm- .atesurfaces of the members are engaged with one another in drivingrelationship. An outer arm is rigidly secured at one end to the shaft.The outer arm has a length equal to the length of the other inner armbetween the shaft and the base. A second shaft is rotatably mounted atthe other end of the outer arm with a limbing head rigidly secured tothe shaft. Means connecting the first and second shafts cause the secondshaft to move through the same angle relative to the outer arm as theinner arms move relative to the base. Movement of the inner armsrelative to the base causes the limbing head to travel in a straightline at a constant angular attitude relative to the base.

7 Claims, 4 Drawing Figures PATENTEDJAN 23 I975 SHEET 1 [IF 4PATENTEDJAH23 197s sum 2 [1F 4 PATENTEDJAH 23 I973 SHEET 3 [IF 4 LIMBINGBOOM This invention relates to limbing assemblies for removing limbsfrom trees.

The limbing of trees is frequently carried out by movement of a limbinghead along the tree with a power sufficient to cause the limbing head toremove limbs from the tree when the limbing head engages the limbs, thelimbing head usually having suitably shaped leading surfaces tofacilitate detachment of the limbs from the tree. Various mechanismshave been proposed for moving the limbing head along the tree, but suchknown mechanisms have been somewhat cumbersome and hence not easy totransport from one place to another. Also, it has been a problem toeffectively transmit the necessary power to the limbing head at allstages of its travel along the tree.

It is therefore an object of this invention to provide a limbingassembly which overcomes the above-mentioned disadvantages.

According to the invention, a limbing assembly includes a pair ofparallel inner arms pivotally connected to a base. The inner armspivotally carry and are linked to an outer arm in such a manner that,when the inner arms move through an angle relative to the base, theouter arm moves through twice the angle relative to the inner arms. Thefree end of the outer arm carries a limbing head, and a linkageconnecting the limbing head and the inner arms ensures that, during thepreviously mentioned angular movement of the various arms, the limbinghead moves angularly relative to the outer arm by the same amount thatthe inner arms move relatively to the base.

In this manner, angular movement of the inner arms relative to the basecauses the limbing head to travel in a straight line at a constantangular attitude relative to the base.

One embodiment of the present invention will now be described, by way ofexample, with reference to the accompanying drawings, of which,

FIG. 1 is a side view of a limbing assembly in one position,

FIG. 2 is a similar view of the limbing assembly in another position,shown FIG. 3 is a front view of the limbing assembly in the positionshown in FIG. 2, and

FIG. 4 is a side view of the limbing assembly in a third position.

Referring to the drawings, a limbing assembly includes a base 1 mountedon a chassis 2 of a logging machine. For ease of explanation, thisembodiment will be described in connection with the limbing of asuitably held horizontal felled tree. However, it will be understoodthat the base 1 may be mounted on the by shafts 9, 10 respectively. Thusthe arms 4,5, the links 8 and the portion of the base 1 between theshafts 6,7 form a parallelogram linkage, with the result that the arms4,5 always remain parallel to each other during their angular movementrelative to the base 1, and the links 8 always remain parallel to theline between the shafts 6,7. Angular movement of the arms 4,5 relativeto the base 1 is effected by a hydraulic jack 11 having one endpivotally connected to the arm 4 by a pin 12 and the other end pivotallyconnected to the base 1 by a pin 13. The jack 11 passes through anaperture 14 in the arm 5.

The shaft 9 carries an outer arm unit 15 which includes an arm 16 equalin length to the arms 4,5 and rigidly secured at one end to the shaft 9.The other end of the arm 16 carries a limbing head 17 for removing limbsfrom trees. The actual construction of the limbing head 17 is not afeature of this invention and will chassis for pivotal movement relativethereto so that the assembly can limb a tree at an inclined angle. Theembodiment to be described may be used as the limbing assembly on thelogging machine described in our Canadian Pat. No. 835,144 issued Feb.24, I970 and entitled Feller-Limber-Buncher Logging Machine". It canalso be used, when mounted in a position perpendicular to that shown, tolimb a standing tree.

The base 1 carries an inner arm unit 3 formed by two spaced parallelarms 4,5 pivotally connected at one end to the base 1 by shafts 6,7respectively and pivotally connected at the other end to opposite endsof links 8 therefore not be described further. However, a suitablelimbing head is described in our patent application referred to above.

The limbing head 17 is rigidly secured to a shaft 18 rotatably mountedin the other end of the outer arm 16. The shaft 18 carries a sprocket 19rigidly secured to the shaft 18, and an endless chain 20 passes aroundthe sprocket 19 and around a sprocket 21 of the same size as thesprocket 19 carried by and rigidly secured to the shaft 9 at theopposite end of the arm 16. The shaft 9 is rotatably mounted in the arm4 and links 8 and carries a gear segment 22 which is rigidly secured tothe shaft 9. The gear segment 22 meshes with a similar gear segment 23carried by and rigidly secured to the shaft 10, which in turn is rigidlysecured to the arm 5.

In FIGS. 1, 2 and 4, the horizontal line 24 indicates a felled treewhich is held by some convenient means (not shown) which may be, forexample, the felling head described in our previously mentioned patentapplication. Assuming that the limbs of the tree 24 are to be removed bymovement of the limbing head 17 from right to left, the jack 1 l isactuated to position the limbing assembly in the attitude shown in FIG.1, and the limbing head 17 is engaged with the tree 24. If desired, thelimbing head 17 may be capable of some initial angular adjustmentrelative to the tree 24 and to the shaft 18, for example by means of alinkage including a hydraulic jack. For the actual limbing operationhowever the limbing head 17 is effectively rigidly secured to the shaft18. When the limbing head 17 has been suitably positioned with respectto the tree 24, the jack 11 is extended to cause the inner arm unit 3 toswing from the position shown in FIG. 1 through the central positionshown in FIG. 2 to the position shown in FIG. 4. During this angularmovement, the gear segment 22 is caused by its engagement with gearsegment 23 to rotate about the axis of shaft 9, thereby rotating shaft 9with consequent angular movement of the arm 16 relative to the inner armunit 3 to cause the limbing head 17 to travel in a straight line alongthe tree. Also, the rotation of the shaft 9 causes a similar rotation ofshaft 18, due to the connection by'chain 20, such that the felling head17 moves angularly relative to the outer arm 16 so as to remain in thesame angular attitude relative to the tree 24. In this way, the limbinghead is moved along the tree 24, thereby removing its limbs. It will beseen that, as the arms 4,5 move through an angle relative to the base 1,the arm 16 moves through twice this angle relative to the arms 4,5, andthe limbing head 17 moves through the original angle relative to the arm16.

Iclaim:

1. A limbing assembly for removing limbs from a stationary tree,including a base, a pair of parallel inner arms pivotally connected tothe base, means for pivoting the inner arms relative to the base, meansfor maintaining the inner arms in their parallel relationship duringsuch pivotal movement, a first arcuately-surfaced member rigidly securedto one inner arm, a shaft rotatably mounted in the other inner arm, asecond arcuately-surfaced member rigidly secured to said shaft, thearcuate surfaces of said members being engaged with one another indriving relationship, an outer arm rigidly secured at one end to theshaft, the outer arm having a length equal to the length of said otherinner arm between said shaft and the base, a second shaft rotatablymounted at the other end of the outer arm, a limbing head rigidlysecured to said shaft, and means connecting said first and second shaftscause the second shaft to move through the same angle relative to theouter arm as the inner arms move relative to the base, whereby movementof the inner arms relative to the base causes the limbing head to travelin a straight line at a constant angular attitude relative to the base,

2. A limbing assembly according to claim 1 where each arcuately-surfacedmember is a gear segment 3. A limbing assembly according to claim 1wherein the inner arms are maintained in parallel relationship by a linkhaving opposite ends pivotally connected to the arms.

4. A limbing assembly according to claim 3 wherein shaft and at theother end on a third shaft carried by said one inner arm.

5. A limbing assembly according to claim 4 wherein the firstarcuately-surfaced member is rigidly secured to said third shaft, andsaid third shaft is rigidly secured to said one inner arm.

6. A limbing assembly according to claim 1 wherein the means forpivoting the inner arms includes a hydraulic jack pivotally connected atone end to one of the inner arms and at the other end to the base.

7. A limbing assembly according to claim 1 wherein said means connectingsaid first and second shafts includes a first sprocket rigidly securedto the first shaft, a second sprocket rigidly secured to the secondshaft, and an endless chain passing around said sprockets.

1. A limbing assembly for removing limbs from a stationary tree,including a base, a pair of parallel inner arms pivotally connected tothe base, means for pivoting the inner arms relative to the base, meansfor maintaining the inner arms in their parallel relationship duringsuch pivotal movement, a first arcuately-surfaced member rigidly securedto one inner arm, a shaft rotatably mounted in the other inner arm, asecond arcuately-surfaced member rigidly secured to said shaft, thearcuate surfaces of said members being engaged with one another indriving relationship, an outer arm rigidly secured at one end to theshaft, the outer arm having a length equal to the length of said otherinner arm between said shaft and the base, a second shaft rotatablymounted at the other end of the outer arm, a limbing head rigidlysecured to said shaft, and means connecting said first and second shaftscause the second shaft to move through the same angle relative to theouter arm as the inner arms move relative to the base, whereby movementof the inner arms relative to the base causes the limbing head to travelin a straight line at a constant angular attitude relative to the base.2. A limbing assembly according to claim 1 where each arcuately-surfacedmember is a gear segment
 3. A limbing assembly according to claim 1wherein the inner arms are maintained in parallel relationship by a linkhaving opposite ends pivotally connected to the arms.
 4. A limbingassembly according to claim 3 wherein the link is pivotally mounted atone end on said first shaft and at the other end on a third shaftcarried by said one inner arm.
 5. A limbing assembly according to claim4 wherein the first arcuately-surfaced member is rigidly secured to saidthird shaft, and said third shaft is rigidly secured to said one innerarm.
 6. A limbing assembly according to claim 1 wherein the means forpivoting the inner arms includes a hydraulic jack pivotally connected atone end to one of the inner arms and at the other end to the base.
 7. Alimbing assembly according to claim 1 wherein said means connecting saidfirst and second shafts includes a first sprocket rigidly secured to thefirst shaft, a second sprocket rigidly secured to the second shaft, andan endless chain passing around said sprockets.